Algae carpet in front of Eriskirch on Lake Constance
Photo: Felix Kästle / dpa
A seemingly infinite number of shades of blue, ranging up to emerald green and colors reminiscent of the Caribbean - that's what Lake Constance, the largest inland body of water in Germany, is known for.
What is he not known for?
Green, threadlike carpets of algae that stink and scare off bathers.
The carpets grow in places where there are many nutrients and where the water is warm, writes the Baden-Württemberg State Institute for the Environment in a statement.
The Schussen estuary near Langenargen is currently affected: currents and wind could distribute the nutrient-rich water in the estuary, and the water is relatively flat and can warm up quickly.
The nutrient content in the Estuary of the Schussen is also so high due to agriculture and sewage, which promotes the growth of algae.
In Eriskirch and in protected port facilities, green areas have also been observed in the water in the past few days.
The alga is harmless to humans
The algae consist of multicellular threads, as the state institute writes.
These would form a network structure – which would have given the alga the name “water network” (Hydrodiction reticulatum).
However, the algae are harmless to humans.
At least when it comes to health.
Because for the surrounding communities, the "water networks" are a nuisance: At some bathing spots, hardly any people would dare to go into the water, reports the SWR.
»The hoteliers, hosts and citizens have their houses right on the lake.
The smell affects everyone," the broadcaster quoted the head of the tourism office as saying, Alexander Trauthwein.
According to a message, the mayor of Langenarg, Ole Münder, says that the intensity of the stench was very high - for this reason, numerous guests and residents could not have stayed outdoors for long.
Such "disruptions" would have existed before - but rain could have mostly replaced them, according to the municipality of Langenargen.
Münder assumes that such algae occurrences could increase in the future: »With regard to the local climate development, we will not only notice these effects intensively and more frequently on the DLRG beach and in the lido, it will also extend to many places in the west along the shore of Lake Constance«.
Various attempts to remove the algae
How do you get rid of the green carpets?
The local communities are currently looking for solutions to this.
In Langenargen, for example, several mechanical options are being tried out: an excavator that drives into the water and takes out the algae or a suction device, as reported by SWR.
On Monday, an attempt to get the algae out with a towing vehicle failed.
Meanwhile, in Langenargen and Eriskirch, consideration is being given to using oil barriers to keep the algae away from the shore.